1. Field of the Invention
This invention relates to a medical device and, in particular, to a delivery and deployment device for a prosthesis and a method of deploying a prosthesis in a body lumen.
2. Description of Related Art
Endoluminal prostheses, such as stents and stent grafts, are used for treating damaged or diseased body lumens such as the esophagus, bile duct, and blood vessels. For example, endoluminal prostheses may be used for repairing diseased aortas including abdominal aortic aneurysms and thoracic aortic aneurysms. Such a prosthesis is placed inside the body lumen and provides some or all of the functionality of the original, healthy vessel.
The deployment of endoluminal prostheses into the lumen of a patient from a remote location by the use of a catheter delivery and deployment device is well known in the art. For example, PCT Patent Publication Number WO 98/53761 entitled “A Prosthesis and a Method and Means of Deploying a Prosthesis,” which is incorporated herein by reference, proposes a deployment system for an endoluminal prosthesis. The prosthesis is radially compressed onto a delivery catheter and is covered by an outer sheath. To deploy the system, the operator slides or retracts the outer sheath over the delivery catheter, thereby exposing the prosthesis. The prosthesis expands outwardly upon removal of the sheath. Such a delivery and deployment device has been referred to as a “push-pull” system because as the operator pulls the sheath proximally in relation to the delivery catheter, the delivery catheter pushes the prosthesis out of the sheath.
Devices, such as the ones described in WO 98/53761 have several advantages. To deploy the prosthesis, the operator can directly manipulate the sheath and the delivery catheter. This provides the operator with a relatively high degree of control during the procedure. Further, such devices may be compact and may have a relatively uniform, low-diameter radial profile, allowing for atraumatic access and delivery.
In order to provide a low-diameter profile, the delivery catheter, the sheath, and the prosthesis are often very tightly interconnected. As a result, manual retraction of the sheath may be challenging. An exemplary delivery and deployment device may require as much as 100 Newtons (N) or approximately 22.5 pounds of force to deploy. Such resistance can easily tire an operator and accordingly is highly undesireable.